In2S3-decorated TiO2 nanotubes with a Type-II heterojunction for enhanced photoelectrochemical cathodic protection of 316L stainless steel

In this study, TiO2 nanotubes decorated with In2S3 films were fabricated by anodic oxidation followed by hydrothermal deposition. Under optimized conditions (2 mmol precursor, 12 h), the TiO2/In2S3 photoanode delivered a photocurrent density of 3 μA cm−2 and a photovoltage drop of 400 mV under AM 1.5 G irradiation, demonstrating enhanced photoelectrochemical cathodic protection. In addition, the composite exhibited strong photocatalytic antimicrobial activity. Plate count assays showed a dose-dependent bactericidal effect, achieving bacterial elimination at 2.5 mg/mL under illumination, while exhibiting negligible dark toxicity. Mechanistic analysis indicated that the type-II heterojunction promotes charge carrier separation and inhibits recombination, thereby improving both photoelectrochemical cathodic protection and antibacterial performance.